A Guide to Hazardous Area Classification


An Industrial area is many times classified according to the fundamental components involved. Flammable gases, combustible dust, mists, etc can create an explosive environment in the industry. The combination of a flammable substance, an oxidizer like open air and a source of ignition like a spark, flame or excessive heat can create an explosion.

How to Prevent Explosions?

The main aim of dealing with any hazardous area is to make sure that explosion is prevented,

One way to do this is to enclose the equipment which is the source of heat or current in an explosion-proof enclosure to prevent the explosion from spreading.

Another way is to remove the source of spark altogether by using a device which does not produce enough heat to cause combustion and explosion.

The last approach is to completely isolate the explosive device from ignition material.

How to Ensure Safety in Hazardous Area:

Every industry will have a certain operation which may be hazardous. To prevent such a hazardous environment from developing there are many regulations and guidelines in the industry. The type of equipment safe to use in such an environment is regulated by various bodies. ATEX (ATmosphere EXplosible) provides a standard which is recognized internationally hence choosing the right ATEX certified equipment is non-negotiable.

What is ATEX?

Directive 2014/34/EU applies to the manufacture of products which are used in potentially explosive atmospheres. Consequently, the manufacturer has sole responsibility for ensuring that any products falling within this category comply with the Directive. The ATEX Directive applies to all electrical and mechanical equipment and protective systems which are located within potentially explosive environments.

The Five main Categories of Hazardous Area Equipment:

1. Equipment group:

A piece of equipment can be classified by its application. For example, it is classified as I if it is used in underground mines, oil refinery, oil rigs, etc and it is marked as II if it is used for a paper mill, the textile mill, etc.

2. Zone Classifications

This indicates the type of atmosphere for which the equipment has been classified, Zone 0, 1 or 2. Zone 0 relates to combustible gas, Zone 1 relates to fumes and Zone 2 relates to mist. So, if the equipment has been classified as Zone 20 it means that it is classified for an atmosphere of combustible dust.

The most hazardous of all is Zone 0 or Zone 20 where the equipment intended to be used is placed in an atmosphere which is explosive continuously or over a long period and is marked as Category 1 equipment. Zone 1 and 21 is the area where the equipment intended to be used is placed in an environment where an explosion may likely occur during normal operation and the equipment should be marked as Category 2. Zone 2 or 22 is relatively less hazardous, and the equipment intended to be used in this area where combustible gases are usually not present or only persist for a short duration and the equipment should be marked as category 3.

3. Gas Groups

The next category is gas groups based on the gas present in the atmosphere.

Group I: Equipment is used in underground mines where the atmosphere contains combustible dust.

Group II: Equipment used in an explosive atmosphere other than underground mines.

4. Temperature Classes and Ambient Temperatures

An important electrical equipment classification is the temperature of its surface which may be exposed to the hazardous environment. The surface temperature should be tested such that it does not exceed 80% of the ignition temperature of the gas or vapor which is present in the area. The temperature is classified from T1 to T6 based on the equipment surface temperature.

5. Types of Protection:

The various types of equipment are placed in enclosures and protections in the hazardous environment and the enclosure is labeled as per the protection it provides. There are 8 types of protections listed in ATEX but the most common ones are;

d-Flameproof – An internal explosion of the equipment is contained within the enclosure and does not spread outside. Can be used in Zone 1.

Ia– Intrinsically Safe- The energy of the device is limited such that it becomes impossible for combustion to occur even when flammable material is present by effectively removing the source of ignition. This protection level is suitable for use in Zone 0

e– increased Safety -Used in Zone 2 or 1There are many hazardous area regulations available based on the various regions but buying industrial components which is ATEX certified is preferable as it is an internationally approved standard. Eltavle Producent (switchboard manufacturers) Titech are one of the few who can offer ATEX boards in Denmark. Following hazardous area regulations is unavoidable if you intend to prevent disastrous explosions and accidents.